Chapter 114- Refrigerants Flashcards

1
Q

Liquid refrigerants are defined as

A

Liquids that, atmospheric pressure, have a boiling point considerably lower than that of water

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2
Q

There are six groups of refrigerant

A

B1, b2, b3, a1, a2, a3

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3
Q

The B group is characterized by its

A

Toxicity

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4
Q

The A group is characterized by its

A

Low toxicity

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5
Q

The number determines its

A

Flammability

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6
Q

A1 is defined as

A

Non toxic, non flammable

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7
Q

A2 is defined as

A

Flammable, low toxicity

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8
Q

A3 is defined as

A

Low toxicity, highly flammable

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9
Q

B1 is defined as

A

Highly toxic an non flammable

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10
Q

B2 is defined as

A

Flammable and highly toxic

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11
Q

B3 is defined as

A

Highly flammable, highly toxic

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12
Q

Ideal refrigerants have these qualities

A

Low boiling point at atmospheric pressure
Low condensing pressure
An inoffensive odour
A non poisonous nature
Non corrosive action on metals
Nonflammable and non explosive nature when mixed with air
Reasonable price

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13
Q

Thermodynamic properties include

A
Pressure
Temperature
Volume
Density
Enthalpy
Entropy
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14
Q

What is the pressure temperature relationship of refrigerants

A

The saturation temperature of a liquid in a closed vessel can be raised or lowered by raising or lowering the pressure in a vessel.

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15
Q

What are standard conditions of a refrigerant

A

Standard evaporator temperature of -15 degrees Celsius

Standard condenser temperature of 30 degrees Celsius

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16
Q

Specific volume is defined as

A

It is necessary to know the specific volume of a refrigerant while it is a liquid or a vapour under conditions required in the refrigerator it’s specific volume is the the change in volume between states

17
Q

Density is defined

A

The density of a liquid refrigerant, required to know the size of valves and piping in a refrigerator. Expressed in kg/ meters cubed

18
Q

Enthalpy is defined as

A

Sensible heat in a liquid

Sensible heat plus latent heat in a vapour

19
Q

Refrigerating effect

A

The effect of heat being taken away from the surroundings so that cooling may take effect, vapour to a gas requires latent heat energy this is what causes the cooling effect in a refrigerator

20
Q

Physical properties of refrigerants

A
Miscibility
Leakage tendency
Odour
Toxicity 
Flammability/ explosiveness
Moisture reaction
21
Q

Miscibility is defined as

A

The ability of oil to be absorbed into a refrigerant and vice versa is miscibility

22
Q

Leakage tendency is defined as

A
The leakage tendency of a liquid may include factors like
Operating pressure
Viscosity
Density
Molecular mass of the refrigerant
Larger the molecule, the less of a chance it has to escape
Fat kids can't run
for long
23
Q

Odour is

A

What you smell
Idiot
Used to detect is a refrigerant leak is taking place

24
Q

When a halide torch is us for leak detection what should be done

A

Provide ample ventilation

25
Toxicity is defined as
When e posed to a flame the may react and decompose forming highly toxic vapours, or may be highly toxic to begin with Will fucking kill you
26
Moisture reaction must be avoided for two reasons
May cause ice to form between valve and valve seat Could result in corrosion Sludge forming Deterioration of the motor insulation